Radioactivity in Medicine and Other Applications

Radioactivity is often perceived as dangerous however, it is also immensely useful to physicians in the diagnosis and treatment of disease and has numerous other valuable applications. The use of radioactivity in medicine can be broadly divided into diagnostic techniques (which diagnose disease) and therapeutic techniques (which treat disease). 

Such scans are often used to locate cancer that has metastasized (spread) to the bones from a primary tumor elsewhere. 

The use of radioactivity in diagnosis usually involves a radiotracer, a radioactive nuclide attached to a compound or introduced into a mixture in order to track the movanent of the compound or mixture within the body. Tracers are useful in the diagnosis of disease because of two main factors (1) the sensitivity with which radioactivity can be detected, and (2) the identical chemical behavior of a radioactive nucleus and its nonradioactive counterpart. For example, the thyroid gland naturally concentrates iodine. When a patient is given small amounts of iodine-131 (a radioactive isotope of iodine), the radioactive iodine accumulates in the thyroid, just as nonradioactive iodine does. However, the radioactive iodine emits radiation, which can then be detected with great sensitivity and used to measure the rate of iodine uptake by the thyroid, and thus to image the gland. 

A specialized imaging technique known as positron emission tomography (PET) employs positron-emitting nuclides, such as fluorine-18, synthesized in cyclotrons. The fluorine-18 is attached to a metabolically active substance such as glucose and administered to the patient. As the glucose travels through the bloodstream and to the heart and brain, it carries the radioactive fluorine, which decays with a half-life of just under 2 hours. When a fluorine-18 nuclide decays, it emits a positron that immediately combines with any 

Nuclide Type of Emission Half-Life Part of Body Studied 

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Radioactivity in Medicine and Other Applications 940 Key Learning Outcomes 944... 

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